Refrigeration system with multiple stage ejector



5, 1952 H. A. BURGGRABE 2,605,613

REFRIGERATION SYSTEM WITH MULTIPLE STAGE EJECTOR 3 Sheets-Sheet 1 Filed Aug. 18, 1949 REFRIGERATION SYSTEM WITH MULTIPLE STAGE EJECTOR Filed Aug. 18, 1949 g- 1952 H. A. BURGGRABE IS Sheets-Sheet 2 Jaye/liar Hell? Afiwyrak 1952 H. A. Bl JRGRABE 2,605,618

REFRIGERATION SYSTEM WITH MULTIPLE STAGE EJECTOR Filed Aug. 18, 1949 s Sheets-Sheet a Patented Aug. 5, 1952 UNITED STATES r REFRIGERATION sYs'rEMwrri i Mamie STAGE EJECTOR Henry A. Burggrabe, Detroit, Mich, assigncr, by mesne assignments, to Stator Company,'a -cr-" poration of Massachusetts Application August 18, 1949, Serial No. 111,055 i ()laims. (Cl. 62-11735) This invention rleates to an improved refrigere ation system of the type shown in United States Patent No. 2,174,300, granted September 26,1939.

Such systems usually employ water as a refrigerant and mercury as a propellant, and while water and mercury are immiscible under ordinary conditions, under certain operating conditions fine particles of mercury become suspended in the water toform a mud-like sludge, as is more fully. explained in theabove-mentioned patent. Such sludge tends to impede circulation and provision must be. made to minimize its formation, to remove and. break up accumulations of such sludge, andto return the mercury component to the boiler or propellant circuit without impairing the operating efficiency of the refrigerating system. To this end the system shown in the abovementioned patent has proved successful, but it will be noted that the arrangement is relatively complicated, bulky and expensive. Moreover, since such systems are also used to provide a a suitable antifreeze agent.

supply of hot water, provision must be made to transfer the heat of condensation of the propellant and refrigerant fluids to :a suitable water supply, .as shownfor examplein United States Patent No. 2,174,302, granted September ,26, 1939. It is, of course, highly desirable to operate such systems so as to maintain a high refrigeration Referring to Fig. 1, the refrigerating system;

1 shown therein comprises a boiler I having a suit? able heater such as a gas burner assembly 2 and a draft-inducing flue 3, only a portion ofwhich is shown. Mercury vapor passes from the boiler i through a riser 5 'to'the branches 5a and 5b which are connected respectively to the interconnected first and second'sta'g'e" aspirators 6a and 6b of my improved multiple stage ejector. The first stage aspirator "6a is connected by a vapor duct 8 to the cooler or'evaporator" H which con} tains a body of aqueous refrigerant containing Vapor is drawn through the'duct 8 to the mixing'chamb'er of the first stage aspirator (hereinafter more fully described) and the mixed propellant mercury vapor and the refrigerant vapors are passed through the aspirator where the refrigerant is compressed and the mercury is condensed.

The condensed mercuryflows from the" first stageaspirator into a drain [4 while the compressed vapor passes to the second stage aspirator "6b into which a second stream of mercury vapor flows from the. line5b,.ithisflatter. propellant stream causing further 7 the refrigerant vapor in thesecond stage aspirator. A drain 2"! receives the condensed mercury from the second stage aspirator and the two efilciency and heat transfer, and yet prevent the objectionable accumulation of mercury sludge. The principal objects of the present invention are to simplify the above systems and to provide an improved multiple stage ejector having efficient and reliable means for eliminating sludge and for transferring or dissipating heat, and which is relatively inexpensiveto manufacture and install.

Another object iS'tO minimize the amount of propellant passing from the first stage tothe second stage ejector. V

Further objects relate-to various features of construction and will be apparent from a consideration of the following description and the accompanying drawings wherein:

Fig. 1 is a diagrammatic view of a refrigerating system embodying the present invention;

Fig. 2 is a longitudinal section view through 1 the multiple stage ejector; V

Fig. 3 is an end elevation of the ejector; a

Fig. lis an enlarged-section on the line l -4 of Fig. 2;

Fig. 5 is a fragmentary elevation with parts broken away, of the outer end of the first stage ejector; and

drains it and 21 converge. at 2 8. The compressed refrigerant passes upwardly from thesecond stage aspirator through duct 29 to the refrigerant condenser 30. The condenser'39 maybe of any suitiable form and is here shown as being disposed within a water tankjor reservoir T, as in Patent No. 2,174,302, granted September 26, 1939.

A chamber crdrum 32 is preferably located at the end of the condenser 30 which is remote from the inlet of the pipe 29 and one end of a pipe 39 communicates with the chamber 3 2150 asfto receive noncondensable gases therefrom. The lower, portion of this chamber is connected with a drain or refrigerant return pipe 34 through which the condensed refrigerant passes on its way back tothe cooler llf I" The lower end of the pipe 316 .is'.co'nnect ed to an inclined tube 40, the'upper end of which has a verticalcontinuation t2 which extends above the level of the liquid L in thecooler H. The pipe section 42 has a connection with a down}, wardly extending pipe 13, the lowerend of which is connected with a drain duct 44 communicating with the lower partof the cooler II. The lower part of the cooler H is formed with walls which incline downwardly toward the drain 44 so that accumulations of mercurysludgein the cooler H may passdirectly into the drain 44. j j The lower part of the duct 44 provides a shallow compression of 3 trap communicating with a drum or chamber 50. The duct 44 has a relatively large diameter to permit the movement of the heavy sludge therethrough and the drum 50 extends downwardly a substantial distance below its connection with the trap defined by the duct 44. The upper part of the drum 50 is connected by vapor duct 5I to the low-pressure portion of the system, i. e., the upper part of the cooler I I. An upwardly inclined duct 52 extends from the lower part of the drum 5D and is connected at 53 with the vapor duct 5I. Below the connection 53 is a spill-over duct 55, the lower part of which provides a trap 56 connected to a mercury return 51 which is connected with the boiler I.

When sludge accumulates in the cooler ii, it forms a mud-like deposit on the lower walls of the cooler and since the cooler is provided with downwardly sloping walls this heavy, mud-like deposit can drain into the drum50. Since the drum 50 is'connected to the low-pressure portion or the system and is in a relatively warm location, the more volatile element of the heavy sludge, i. e., theaqueous refrigerant, is evaporated and drawn into the first stag mixing chamber through the duct 8; while the mercury residue flows into the line 52 and thence, into the spillover 55 to the mercury return 51. Since the drum 5!] extends a substantial distance below the spillover connection into the line 55, any sludge in the, lower part of the drum is subjected to a substantial liquid head which results in a tendency to squeeze refrigerant out of the sludge so that the mercury may coalesce.

The connection 28 between the drains I4 and 21 communicates with a small drum or cham ber. SI to which the lower end'of the inclined pipe is also" connected, while an upwardly inclined duct BI extends from this chamber to a chamber 54 constituting apart of the purger assembly 63. The chamber 64 receives noncon densablejgases through the pipe' 39 and a drop tube of restricted interna1 1 diameter; extends downwardly therefrom. Globules of condensed 1 mercury spilling over fromithe duct-GI entrain bubbles of the noncondensable gases in the-tube 65; compressing thexgases as'they move downwardly through the tube; V The lower endof the tube 65 is immersed in'a body of mercury in the wellfil', the. upper surfa'ce of this liquid propellant beingexposedto' atmosphere. A return duct 69 is circumposed about the'tube 65 and is C011? nected to the mercury-return pipe 51, there being a very small pressure-equalizing vent between the upper part of the duct 69 and chamber 64. A deflector 68 prevents gas from rising into '30 and the evaporator II.

cury column of constant height is automatically maintained in the leg 21 of the trap, since the vapor spaces above the mercury in the pipe 21 and in the pipe 39 both lead into the condenser 30, and are therefore at the same pressure. These mercury columns are balanced by the mercury in pipe 49 which fills pipe 46 up to its intersection'with pipe 34, plus the condensed refrigerant liquid in pipe 3 Mercury rises in the vertical pipe 42 to a sufiicient height to balance the pressure difierence between the condenser The condensed refrigerant rises in pipe 34 until sufficient head is built up to allow some of the liquid to pass into pipe 42 and rise through the mercury therein, and then pass into the evaporator via pipes 43 and 44. The liquid heads in the branches 34 and 42 are provided by bodies of condensed mercury and aqueousreirigerant, as explained more fully in Patent No. 2,174,360, granted to Lyman F. Whitney, September 26, 1939, to-which reference may be had for a more complete-description of the operation of the system. 1

In accordance with the present. invention, the first andjsecond stage aspirators and their associated parts provide an interconnected assembly which, as shown in Figs. 2 to 4, comprises an elongate housing of cylindrical shape and formed in two sections, one the inner section I00 having a closed rear end MI and the outer section IDDa having an open front end I02 which receives the first stage aspirator I03. The flower bottom wall I 94 of the first section of the housing slopes slightly from the fronttoward the rear so. that condensate accumulating therein. runs toward the rear wall IOI.

The ejector or aspiratcr Iii-3 may be of .the

same general design as shown in Patent No.

1,756,802, granted April 29,. 1930, comprising an elongate diffuser H!) the enlarged. end III of which is in spaced axialalignment with a nozzle II2 connected with the branch 50. of the riser 5. The space between the nozzle and funnelcone stitutes a mixing chamber surround-ed by a perforate casing or sleeve II3 which is disposed within a dome-like closure or. cap II5 which is formed with an enlarged inlet opening II'Ito re- 1 ceivethe vapor duct 8. Each of theperforations opening.

the duct 69 fromthe lower end of the drop tube The arrangement of the spill-=over'connection between the tube GI and chamber 64 determines the level of the mercury in'the trap defined by the lower parts of the ducts 34 and 42; The condensedmercury received from the, drains I I-and 27 passes into the chamber 60 and from the lat ter' may pass to thespill-over connectionand thence to the purger. From thepurger the mercury flows through the pipe 51 back to the boiler I, the height of the mercury in the pipes 51 and 69 being suflicient to balance the boiler pressure.

During normal operation of the system the trap defined by the pipes BI and 40 is constantly receiving condensed mercury from the drains I4 and 21, and the spill-over connection between pipe 6| and chamber 64 definitely limits the height of mercury in the pipe 21. Thus, a mer- I I4 in the sleeve I I3 is considerably smaller than the inlet opening I I1 communicating. with the duct 8, but the combinedareaof the perforation is substantially greater than that of the inlet Throughout the major portion of its length the exterior wall of diffuser. I I I] is provided with heat-dissipating fins H5 and ajac'ket II8 surroundsthat portion of the diffuser within this section I00, this jacket having a. plurality of longitudinally extending fins. II9 ;about itsexterior wall. The jacket II8 thus defines. with section I09 a discharge chamber I20 through which the vapors from the diffuser I II] pass, and with section Ififiwdefines a cooling fluid chamber I2I substantially coextensive with and surrounding the diifuser IIll. The floor of the section I adjacent to theend IIJI is formed with an outlet I22- to which the drain I4 is-connected andthe inner end of the sectionlflll at a point spaced above its fioor-is provided with a vapor discharge opening I23 to which the duct I24 is connected. The floor of section ll'llla adjacent to its inner end-is formed with an opening I25 to which a duct I 26 is connected and the upper part of this section is formed with a similar opening I21 to which "a duct I28 is connected.

compressed -.vapors from 'l"he;;ejector or aspirator IfiBd .is generally similar to the aspirator liw and comprises an elongate diffuser I I having an inner-endin spaced alignment with a nozzle I3 I: which projects through an opening in a cap I 32" connected: to the branch line 5110f riser. 5. Asleeve 133 extends about the space ion-mixing chamber between the nozzle and difiusen-and this sleeve is'formed'with spaced perforations or inlets so as to providea communication between themixing chamber and an annular intake; chamber I39 defined bythe cap I32 and sleeve -I33.-;'.The intake chamber is connectedto duct'rIZ I so that the first stage ejector are: conducted into the intake chamber .of 1 the second stage ejecton. Each of the perforations inisleeve I33 islconsiderably smaller than the inlet opening communicating with duct-I24, but their combined area is. substantially greater. jacket I34 surrounds-the innerrsection of, the diffuser and defines a-cooling' chamber I35. A second casing I35 surrounds an. outer; ection of. the diffuser and defines adischargechamber ,A series of bailies I38 fit abouirthe inner end of the diffuser. within the chamber I31and their peripheries are shaped so as to permit propellant condensate to ,runtoward the closed endof the casing. The floor of this casingadjacent to its closed end is formed with a drain Opening I48, to which the line 2'! is connected and the oppositeendof the chamber I31 beyond the innermost bame is provided with. a vapondischarge opening IAI to which the vapor line- 29 is connected. The inlet chamber I36 is also provides with a drain opening I42 connested by. line I43 withtheprop'ellant drain It so that condensed particles of mercury or propellant may be returned to thesystems. A The line I43'preferably isiormedwith a. trap I ia which is filledwith mercury so as toprevent any flow of refrigerant vapor, V I v discharge end of the first; stagefejector I'It, through line I43 to inlet chamberISS.

In order to permit the apparatus to have as small an over-all height as possible, it is desirable that the outlet I22fbe above the outlet I40, preferably at least by an amountjcorresponding to the height of a' mercury column equalto the difference between the maximum condenser'pressure' thatcanbe obtained in the operation of the, apparatus, and the pressure that occurs at the outlet of the first stage diffuser at'the' time when the machineis operating at the maximum condenser pressure. The particular arrangementTherein shown permits the attainment of this objective, ",Theinner end of the diffuser within the jacket I34 carries a series of heat-dissipating fins I45 and the upper part. ofthis [chamber is provided with an enlarged opening I45 directly connected with the duct I26. Thechambers I2fI'and'I35 are" filled with alcohol or ,other similar liquid which receives heatffrom thel .gases passing throughjthe difiusers'and the; hot vapor is con?- ductedby in a hot water supply tank T, as shown in Fig.1. v. v I V .7 V 1 The tank T is provided with a connection I leading to the condenser I50 by'means of which the cooling circuit maybe initially evacuated so that'the alcohol'therein may vaporize at'relatively low temperature (around "176 1?.) when the temperature of the waterjaroundthe condenser I59 is 170 F. The tank'T'jis also'provided with an inlet line I56 for receiving incoming the pipe I28, to acondenser I50 located Id. :The compressedwater and new sm l vapor remaining in the outlet ofthe diffuser tering theinlet chamber I39 of the second stage 6 water fromthe suppl hmain anda ho'twater supply-line I51 is -connected withltheupper part of the tank, as-in'PatentINo.." 2;174,302, granted September 26,1939, to which reference may be had for a-inore complete description of this part o f' the system. v w r Y I vI In operation, mercury vapor discharged from the nozzle II2 aspirates water vapor through the duct 8 and carries it throughthe diffuser III), compressing it and discharging the compressed'hot vapor into the interior of the housing I68. A substantial amount of heat is absorbed by the alcohol-in the jacket- I I8, and-any condensed mercury fal'ls-to the bottom of the housmg and eventually passes into the drain pipe vapor and any uncondensed mercury is-drawn-through pipe I2 1 into the second stageaspiratorand. carried through the difiuser I3!) whichresultsin further compressing the water vaporwhich, after. passing about the baffies I38, is dischargedinto the: duct 29. The condensed mercury accumulating in the bottom of-the chambers I28 and I3! is re.- turned to the system through pipes I l and 21, respectively. :-Heat--- irom the secondstage aspirator is absorb'ed by the alcohol in the section I34 and circulates upwardly through the jacket IIS andduct-I28- into the condenser I50 where alcohol vapors are condensed and thus give up their-heat to the water in the tank T," as is more fully described in Patent No; 2,174,302. r a

l An important objective, as above noted, is. the prevention to the greatest practical extent of the formation of mercury sludge, particularly in 'thecondenser, refrigerant return line and associated partsr Although the mechanism ac-' countable forthe formation of mercury sludge is ,not' definitely known, zone explanatory theory-is that mercury particles carried by the mixed vapors disch'arged f-rom the .ej'ectors may carry'ele'ctric charges'which cause the particles on encountering'liquid water in the condenser to'forrna relatively-"stable emulsion or sludge, unless suchcharges are removed or dissipated by contact with hot metal surfaces. In any case it has beenrfound that by passing thehot vapors overheated metallic surfaces, such as a series/ 0f bafiies-zdisposed-about the diffuser of the ejector, the-formation of mercury sludge in condenser and return line is virtually: elimi. nated. I v

In order toobtain improved'pumping efficiency, the mercury vapor passing through the. diffusers should be condensed so that the fluid entering the inlet chamber I39 will contain a minimum amount of mercury vapor and minute particles of condensed mercury. The boiling of the alcohol in the chambers I2I and I35,"which respectively surround the first and second stage diffusers, serves to cool the difiuser walls and furthermore cooperates with the cooling fins major portion of mercury fluid stream leaving the I'Iii. Hence, the fluid eh- I IS :in condensing the ejector contains only a'very small amount of uncondensed mercury vapor.

7 Moreover, the change in the" direction of thefiuid streamdischarged from the end of the diffuser in itstrav el to the inlet chamber I39allows minute particles of condensed mercury to impinge upon the wall WI and as a consequencesuch particles fall to the bottom of the chamberIZI) and pass into the return pipe I i 7 and thereby are eliminated from the fluidv conducted to the inlet chamber I39.

.The fluid leaving the discharge orloutlet of the second. stage diffuser I30 is quite hot, as are also the fins I38 disposed about the diffuser I30. Since the hot fluid must pass about the fins I38 before being discharged through the opening I on its wayto the condenser 30, it is maintained at'an elevated temperature; and it will be noted that the baffles are preferably so designed and arranged that the fluid before being discharged through the opening I 4| passes through a tortuous channel defined by the fins I38 and thus the. hot fluid comes in contact with a heated metallic surface which is believed to be effective ineliminating any static, charge which may be carried by the'mercury particles. Hence, even though minute particles of condensed mercury may be entrained w-ith'the vapors passing through the duct 29, virtually no sludge is formed when the .water vapor condenses.

Certain modifications of the above described system are permissible or desirable. For example, the fins H9 on theyjacket IIB, as shown in Fig. 2, may be made more effective in condensing mercury .vapor and removing particles of condensed mercury from the stream of vapor passing between them if their construction is slightly altered as shown in Fig. 5-. In this modification the outer or free end portions of the fins I I 9a are cut and bent to form oppositely extending parts projecting obliquely from the central parts of the fins, thereby to provide a greater chance for the mercury to comein contact therewith. v

Another desirable modification is shown in Fig. 6, wherein semi-ovoid baffles I58 and I59 are positionediin spaced relation to the discharge end of the diffusers I I0 and I30, respectively, so as to deflect .the mercury particles downwardly and then redirect the fluid streamrearwardly. The bafiie I58 may be spot-welded to the walls of the housing IOI as indicated by the numeral I60, and similarly the baffle I59 may be spot-welded to the end of diffuser I30and the wall of housing I36 as indicated by numeral I6I. In either case the lower: ends of these bafiles are formed with openings or spaced from the bottom wall portion of the respective housings so as to provide passageways I62 andv IEBthrough which condensed mercury may flow directly to the returns I4 and 2I, respectively. 1

While I have shown and described one desirable embodimentof the inventiomit'is to be understood that this disclosure is for the purpose of illustration, and that various changes and modifications may be made without departing fromthe spirit and scope of the invention as set forth in the appendedclaims.

Iclaim: v V

1. In an ejector, an elongate diffuser, baflle elements carried by the outer face of the discharge end portion of said diffuser, a cooling jacket surrounding the intake end portion of said diffuser, said cooling jacket having a port arranged to permit circulation of cooling fiuid into and out of said jacket, a casing surrounding said discharge end portion anddefining with said baffle elements a tortuous path of travel for fluid discharged from said diffuser, a condensate discharge port below the level of the discharge end of said diffuser and a vapor discharge port adjacent to the inner end'of'said baflle elements and disposed above the level of said discharge port.

2. In an ejector an elongate diffuser, bafile elemerits carried by the outer face of the discharge end portion of said difiuser, a cooling jacket surrounding the intake end portion of said difiuser, said cooling jacket having a port arranged to permit circulation of cooling fluid into and out of said jacket, a casing surrounding said discharge end portion and defining with said bafiie elements a tortuous path of travel for fluid discharged from' said diffuser, the lower parts of said baffle elementslbeing spaced from said casing so as .to define a path of travel along the'lower wall portion of said casing, a condensate discharge port below the level of the discharge end of said diffuser and arranged to communicate with said path, and a vapor discharge port adjacent to the inner end of said baflle elements and disposed above the level of said discharge port.

3. In a refrigeration system of the type having a refrigerant fluid circuit including a vapor duct and a condenser duct, a propellant fluid circuit including a pressure source and a-return to said source, and a cooling fluid circuit, a multiple stage ejector comprising a first stage ejector including a diffuser having its intake connected with said vapor duct and a nozzle connected with said pressure source, a housingsurrounding the outer end portion of said diffuser and projecting therebeyond so as to provide a chamber into which said diffuser discharges, a second stage ejector including a difiuser having a'vapor intake communicating with said housing at a point remote from the discharge end of the first stage diffuser, a cooling jacket'surrounding the intake end portion of the second stage diffusen-a conduit connecting the cooling jacket with said cooling fluid circuit, a housing surrounding the discharge'end portion of said second stage diffuser, said housing having a vapor discharge port spaced from the discharge end of said diffuser and a condensate discharge port below the level of the discharge end of said diffuser, a vapor discharge line connecting the vapor discharge port with said condenser duct, a pipe line connecting the condensate discharge portwith a return to said source, and bafile elements interposed between said vapor discharge port and said discharge end of said diffuser.

4; In a refrigeration system of the typehaving a refrigerant fluid circuit including a vapor duct and a condenser duct, a propellant fluid circuit including a pressure source and a return to said source, and a cooling fluid circuit, amultiple stage ejector whereof the first stage comprises a diffuser having its'intake connected with said vapor duct and a nozzle connected with said pressure source, a cooling jacket surrounding at least a part of the outer surface of said diifuser, a housing surrounding the outer end portion of said jacket and projecting therebeyond so as to provide a chamber into which said diffuser discharges,-a second stage" ejector including a diffuser having a vapor intake communicating with said housing at a point remote from the'discharge end of said first stage diffuser, a cooling jacket surrounding ,the intake end portion of said second stage diffuser, conduits connecting the cooling jackets with said cooling fluid circuit, a housing surrounding the discharge end portion of said second stage diifuser so as to provide a second chamber into which it may-discharge, said second chamber having vapor discharge port inwardly of and above the level of'the discharge end of said diffuser and acondensate discharge port adjacent to but below-the level of the dis chargeend of saidldifiuser, baiiie means about said discharge lehdTportion between said vapor 9 discharge port and said condensate discharge port, a discharge line connecting said vapor dis charge port with said condenser duct, and a pipe line connecting a return to said source with said condensate discharge port.

HENRY A. BURGGRABE.

REFERENCES CITED The following references are of record in the file of this patent:

Number 1,116,971 1,972,704 2,008,350

0 UNITED STATES PATENTS Name. Date Barker Nov. 10, 1914 Crosthwait, Jr Sept. 4, 1934 'Dardin et a1 -1- July 16, 1935 Schlumbohm Jan. 3,1939 Whitney Sept. 26, 1939 Whitney Nov. 21, 1939 Whitney Apr. 30, 1940 Pearce Apr. 21, 1942 Hickman Feb. 14, 1948 Goddard Oct. 25, 1949 

